This invention relates generally to sterilizing systems and particularly to sterilizing systems which utilize ozone suspended in a liquid as the sterilizing agent and more particularly to sterilizing systems for endoscopes.
This invention is particularly adapted to endoscope cleaning and sterilization.
Although this invention has tremendous applications to a variety of items to be cleaned including but not limited to, dental tools, surgical instruments, implants, etc., for an understanding of the problems associated with cleansing and sterilization, the following discussion focusses on the cleansing and sterilization of contact lenses.
The success or tragic failure of contact lens wear is ultimately determined by the care and aseptic handling of the lenses. With over seventeen million contact lens wearers in the United States spending two billion dollars on contact lens supplies, a simple one step cleaning and sterilizing process is sought. Both hard and soft lenses currently need daily, or in the case of extended wear contacts, weekly cleaning and antiseptic treatment.
By their very nature, being in close relationship with the wearer for extended periods of time, contact lenses are susceptible to both: buildups of protein and lipids from the wearer; and also from contamination from microorganisms. Either of these, buildup or contamination, can have debilitating affects such as reduced vision, scarring of the eye, and even blindness.
Hydrophilic contact lenses, being soft and composed mainly of water, have made the problem of cleaning even more difficult. Physical pressure on the hydrophilic lense may cause rips; strong disinfectants become lodged within the body of hydrophilic lense itself and then irritate the wearer's eye causing an ulcer.
Without a good cleaning process, both the hard and soft contact lense is susceptible to a wide variety of contaminating microorganisms including:
Acanthamoeba, Pseudomonas organisms, Alcaligenes faecalis, staph, Aureus, and Enterobacter aerogenes. PA1 (1) opens the peristaltic pump housing; PA1 (2) selects an empty capsule of oval cross section; PA1 (3) mounts it horizontally so that fittings on the tilt mechanism mate with the capsule's fittings; PA1 (4) closes and latches the peristaltic pump housing; PA1 (5) connects the two water ports (inlet and drain) and the two gas ports (inlet and vent) on one end of the Capsule to mating connectors on hoses hanging outside the device; PA1 (6) opens the access port door on the other end of the capsule and pulls out the Instrument Rack; PA1 (7) lays out the endoscopic instrument lengthwise on the rack; PA1 (8) adjusts the endoscopic instrument longitudinally to avoid placing any bulky parts in the peristaltic segment of the wash chamber; PA1 (9) installs a compressible, disposable diaphragm on the rack in a location nearest to an approximate midpoint between all the openings in the endoscopic instrument; PA1 (10) inserts the loaded rack with the diaphragm through the open hermetic access port onto a track within the wash chamber of oval cross section PA1 (11) secures the rack by means of a latch on the track; PA1 (12) closes and seals the access port door; PA1 (13) inserts a fresh detergent capsule into the detergent Dispenser; PA1 (14) selects a Wash/Rinse/Sterilize Cycle; and, PA1 (15) presses the "Cycle Start" button. PA1 1) The power is turned on to the unit by the user; PA1 2) The on-board computers checks to see if the pump and ozone generator lamp are off; PA1 3) The computer checks to see how many counts are remaining in the memory count-down; PA1 4) Based upon these checks, the computer, PA1 5) The computer waits a short period of time (i.e. 300 milliseconds) and checks to see that the pump and light are activated; PA1 6) The computer waits another short period of time (i.e. 1 second) and checks to see if gas flow is detected [note- steps 5 and 6 are safety checks to see if the apparatus is working]; PA1 7) After the prescribed amount of time (i.e. 19 minutes) the computer shuts off the ozone generator permitting the pump to continue operation to purge the system; and, PA1 8) After the ozone generator is deactivated, the pump operates a short period (i.e. 1 minute) before the computer deactivates the pump.
For a through understanding of the diseases associated with contact lenses, see: "Pseudomonas aeruginosa Contamination of Hydrophilic Contact Lenses and Solutions", by Milauskas, appearing in Transactions of the American Academy of Ophthalmology and Otology, vol. 76, March-April 1972, page 511; "Complications Associated with Contact Lens Solutions", by Morgan, appearing in Ophthalmology AAO, vol. 86, June 1979, page 1107; "The Soft Plastic Contact Lenses" by Dastoor, appearing the Indian Journal of Ophthalmology, vol. XXI, on page 25; "Microbiological Evaluation of Soft Contact Lens Disinfecting Solutions" by Houlsby et al., appearing in the Journal of the American Optometric Association, vol. 55, Number 3, page 205; and, "Susceptibility of Acanthamoeba to Soft Contact Lense Disinfection Systems", appearing in the Investigative Ophthalmology & Visual Science, April 1986, Vol. 27, page 626.
Additionally, the high water content of hydrophilic contact lenses make them more susceptible to the formation of "jelly bump" deposits which are composed primarily of lipids and calcium. These lipid formations are usually long and intermediate chain cholesterol esters and triglycerides which are particularly difficult to remove from a soft lense without damaging the lense. A good review of this problem is "Origin and Composition of Lipid Deposits on Soft Contact Lenses" by Hart et al., and appearing in Ophthalmology, April 1986, vol. 93, No. 4, page 495.
The typical method of cleaning, using a saline solution and distilled water approach has not been totally satisfactory. It has been found that this approach does not truly address the contamination problem; indeed, several of the contaminating microorganisms actually thrive in the cleaning environments.
Because of this, the industry has been seeking alternative cleaning approaches which may be used by the wearer, not a laboratory.
One technique proposed is the use of a 3% hydrogen peroxide solution for the cleaning and disinfecting the lenses. The reason for this popularity is that after disinfecting, the hydrogen peroxide is converted into innocuous by-products which are compatible with ocular physiology.
The hydrogen peroxide approach is well described in: "A Comparison of New Hydrogen Peroxide Disinfection Systems" by Krezanoski et al., and appearing in the Journal of the American Optometric Association, vol, 59, No. 3, page 193; "Efficacy of Hydrogen Peroxide Disinfection Systems for soft Contact Lenses Contaminated with Fungi", by Penley et al., and appearing in the CLAO Journal, Jan. 1985, vol. 11, no. 1, page 65; "Reaction to Hydrogen Peroxide in a Contact-Lens Wearer", by Knopf, appearing the American Journal of Ophthalmology, June, 1984, page 796; "Hydrogen Peroxide in Anterior Segment [Physiology: A Literature Review", by Chalmers, appearing in Optometry & Vision Science, page 796; and, "Hydrogen Peroxide Sterilization of Hydrophilic Contact Lenses", by Gasset et al., and appearing in Arch. Ophthalmology, vol, 93, June 1975, page 412.
Unfortunately, hydrogen peroxide, at the 3% level or even the 6% level, is incapable of disinfecting some of the hardier microorganisms. Further, hydrogen peroxide does not have noticeable affect upon the "jelly bumps".
Perhaps the most common treatment is the heat method. In this approach the contact lenses are exposed to a temperature of eighty degrees centigrade for a period ten minutes. This approach is more effective than chemicals against microorganisms but the treatment substantially decreases the life of the contact lenses and is usable only with about half of the present contact lenses. Use of this method depends heavily upon the water content and the type of plastic used in the lenses' construction.
Additionally, proteins and other contaminants that are left in the contact lense (buildup) can substantially produce irritation in the eyes of the user.
Although the problems associated with contact lenses are immense, they pale in comparison to the hurdles encountered in cleaning and/or sterilizing endoscopes. Endoscopes are flexible tubes having a multiplicity of endings. Merely soaking endoscopes in a sterilant or detergent is unacceptable since numerous pockets existing within the tubing where the sterilant or detergent cannot effectively reach.
Once used, endoscopes are usually discarded due to the complexity in getting the endoscope sterilized before any subsequent uses. Endoscopes themselves are extremely expensive so their disposal after one use is seen as wasteful since the structural integrity of the endoscope has not been jeopardized by its use, only its sterile nature.
It is clear from the foregoing that an efficient and through cleaning and sterilizing technique does not exist.